The present invention relates to a pallet loading apparatus, and more specifically to an apparatus for loading a pallet carried by one conveyor with articles or containers transferred from another conveyor.
Pallets are extensively used within processing plants to transfer work in process between work stations. In addition, pallets are the mode of choice for conveying raw materials and finished products from one location to another.
In its most rudimentary form, palletizing of articles to be conveyed is accomplished by manual labor—i.e., a human operator manually places an article or articles on a pallet. Of course, manual palletizing is limited by the speed and mobility of the human operator.
Automatic palletizing or stacking of articles on pallets has been around for quite awhile. In an optimum scenario, articles to be stacked and shipped by pallet are transported by conveyor from a finishing station. A second conveyor is provided for discharge of pallets carrying articles stacked thereon. In such an installation, the pallet themselves are fed from a separate supply.
Such a configuration is depicted generally in FIG. 1. Specifically, a series of articles A are conveyed by a conveyor C1 to a transfer apparatus T. A second conveyor C2 transports a pallet P situated thereon. In one typical installation, a series of rollers R disposed within the second conveyor C2 are aligned with a discharge end of the first conveyor C1. The transfer apparatus T transports the article A onto a pallet P when it is situated on the rollers R.
In a typical installation, the article A is conveyed onto the transfer apparatus T by the first conveyor C1. The transfer apparatus T includes a pusher component that pushes the article onto an awaiting pallet. Once the article has been loaded, the second conveyor C2 operates to carry the loaded pallet away.
One problem that must be overcome with an automatic palletizing system is the smooth transfer of the article A onto an awaiting pallet P. In many cases, this transfer can be accomplished by simply pushing the article A directly onto the pallet. However, certain articles, raw materials or products make this approach problematic. For instance, where the article A is a stack of sheet material, this approach is highly unsatisfactory. The lower-most sheets in this stack are prone to being destroyed as they are pushed onto the rough surface of the pallet. Moreover, if enough of the sheet material binds against the pallet, the transfer operation is comprised and can be interrupted.
In one typical prior approach, the stacked article is lifted while a pallet is directed underneath the elevated load. The article is then lowered onto the pallet and the pallet is discharged on an exit conveyor. The patent of Postigo, U.S. Pat. No. 4,764,074 is representative of pallet loading apparatus of this type. As explained more fully in this patent, the stacked article is conveyed to a lifting station where a number of forks, interleaved between conveyor rollers, are slid beneath the stacked articles and used to lift the articles off the conveyor rollers. The pallet is then introduced onto the conveyor rollers directly beneath the elevated load supported by the forks. As the forks are retracted, the load settles onto the pallet for discharge.
One significant difficulty with this approach is that the stacked article or product must be conveyed to the transfer apparatus, lifted and then later dropped onto the pallet. After the load is mounted on the pallet, the lifting forks must be removed before the article and pallet can continue their travel along the discharge conveyor. This approach is much more time consuming than simply pushing the product onto a pallet that is momentarily stopped at a transfer apparatus.
Consequently, there remains a need for a pallet loading apparatus that is adapted to easily convey sheet material onto a pallet. This need encompasses the desire to make this transfer operation occur as quickly as possible to permit high-speed pallet loading.